1. Field of the Invention
The present invention relates to an apparatus for a chemical vapor growth method of a semiconductor device, and particularly to an apparatus for the chemical vapor growth method including gas process means for removing a source gas remaining in the apparatus with high efficiency.
2. Description of the Prior Art
FIG. 1 is a schematic diagram of a conventional apparatus for a chemical vapor growth of a semiconductor device.
The chemical vapor growth apparatus comprises a reaction tube 1, a flow rate control system 3 for supplying reactive gases in respectively predetermined amounts to the reaction tube 1 as a process chamber, a gas trap 5 connected to the outlet side of the reaction tube 1, an exhaust tube 6, a gate valve 7 and a vacuum pump 8.
The flow rate control system 3 comprises a plurality of mass-flow controllers 4.
Next, operation of the conventional chemical vapor growth apparatus having the above construction is explained.
In this case, a dichlorosilane (SiH.sub.2 Cl.sub.2) gas and an ammonia (NH.sub.3) gas are used as a source gas, and a nitrogen (N.sub.2) gas is used as a purge gas.
In tubes except the reaction tube 1, for example, in a dichlorosilane gas supplying tube 9, a main gas line 10, a vacuum vent line 11, an air vent line 12 and a N.sub.2 gas supply tube 13, when the dichlorosilane gas and the ammonia gas are mixed with each other, particles of powdery ammonium chloride are generated. Moreover, these particles attach to the inner walls of these tubes. The tubes are so clogged with these particles that the chemical vapor growth apparatus cannot work at all.
To avoid this problem in the prior art, after the reaction process is finished, the dichlorosilane gas is exhausted by using the N.sub.2 gas supply tube 13 and the vacuum vent line 11, and then the ammonia gas is purged by the combination of the N.sub.2 gas supply tube 13 and the vacuum vent line 11 a little after the purge process of dichlorosilane gas.
However, by this method, the source gas remaining in the mass-flow controllers 4 cannot be removed sufficiently.
Moreover, when other organic gases are used as the reaction gases, since it becomes necessary to probide large-scale heating means for heating the pipeline to prevent moisture condensation, the operation of the chemical vapor growth apparatus. Complicated techniques are required for chemical vapor growth occurring in the apparatus. In this case, the purge of gases remaining in the mass-flow controllers 4 is difficult.
In such a manner, when the remaining gas is not sufficiently purged, the particles as mentioned above are generated in the lines 10, 11, and 12 and the vacuum pump 8 respectively communicated with the mass-flow controllers 4. Accordingly, to avoid the generation of particles in the lines, a large-scale heating system must be required.